The present invention relates to an engine ground system, for example, to an engine ground system that decreases the electric resistance, smooths the flow of electric current, and improves performance characteristics of the engine by directly grounding the ground points of the automotive engine carrying a direct ignition coil of an internal igniter type to a negative electrode terminal of a battery via a ground wire.
A variety of measures have been taken to improve output performance of engines installed on automobiles. For example, a spark tuning system was disclosed in which a mixture inside the combustion chamber of the engine was brought closer to a complete combustion state by connecting the spark plugs by a wire harness having a specific structure and conducting spark tuning of the spark plugs. The applicant has also employed such a spark tuning system in practice. With this technology, engine output is increased by conducting optimum control of the electric current value inputted to the positive electrode terminal side of the spark plug in a state prior to spark plug discharge. On the other hand, the development of a ground system for controlling the minus electric current after a spark plug discharge, that is, after the spark plugs have been activated, is also required.
In the conventional ground system for automobiles, the electric current of a power source is supplied from the positive electrode terminal of a battery to a variety of electric devices such as electronic control devices carried by the automobile, spark plugs, stator motor, instruments on an instrument panel, illumination devices such as lamps, and acoustic devices. Further, after flowing through the electric devices, the electric current flowed through a ground wire connected to the vehicle body and returned to the negative terminal of the battery. As a result, wiring of the wire hardness for electrically connecting various electric devices and the battery was simplified. However, vehicle bodies are usually formed by using steel sheets. Therefore, the conductivity thereof is about one tenth that of copper used for the wire harness, and when the vehicle body is employed for grounding, electric resistance is high. As a result, there is an adverse effect on the spark system of the engine and the engine is greatly hindered from exhibiting its full potential. Another problem is that when the intake flow passes inside the throttle device of an engine intake system, intake air friction causes static electricity, which creates noise hindrance for signal wires of acoustic devices wired in the engine compartment.
Accordingly, the applicant has conducted research and development of an engine ground system for improving the output characteristics of an engine based on the knowledge obtained with the spark plug tuning system that has been heretofore disclosed. As a result, new technology bringing out an engine's full potential has been created.
Thus, with the foregoing in view, it is an object of the present invention to provide an engine ground system that increases an engine's potential by causing the minus electric current after the spark plug discharge to flow smoothly to the ground wire using a constitution wherein the intermediate positions on the ground wire wired between the negative electrode terminal of the battery and the vehicle body are connected to a cylinder head, which is the ground point of the engine, or to a plug cap of a direct ignition coil via this cylinder head.